Asus UX360 dead and soon buried?

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  • ivers
    New Member
    • Oct 2018
    • 7
    • Norway

    #1

    Asus UX360 dead and soon buried?

    Hi!

    I am new to this forum and kind of new to diagnosing electronics.. maybe I have ruined the whole board.
    I guess this is basics, maybe someone could point me in the correct direction for what I could do.

    The laptop is a Asus Zenbook Flip UX360UA only a year old, it has a chassis damage caused not by
    falling or getting hit, but the edge of the screen hitched a table (bad table for laptops) and got bent so the store who sold it
    is not accepting it on warranty. Anyways, what could get worse, was my thought..

    At first when connecting 19v the power led blinked for <200ms and turned off every time.

    The whole board has 19v, the power on button had 3.3v (not anymore), after diagnosing the 19v rail it seemed
    that one of the power supplys didnt get 19v, and I tried to short the mosfet (marked in red), and the laptop powered on,
    charging led started to blink and the screen turned on. Great success... until the laptop turned off, and the
    power led faded away into oblivion..

    Now there is no leds blinking, no 3.3v on power button, bios chip has 0.1v and it's dead. Hearing a click from somewhere
    near the power supply connector. Now the components marked in green heats up to the point where there is not
    possible to touch them, and I guess there is a short somewhere.

    When measuring the caps before and after the mosfets some seems to be shorted, some not. Even caps on the power supplys
    to the right of the board seems shorted.. so I guess I have to buy a capacitor tester?

    Anyways, anyone with a clue of what to do next?



  • piernov
    Super Moderator
    • Jan 2016
    • 4435
    • France

    #2
    Re: Asus UX360 dead and soon buried?

    No boardview available for this board apparently so it makes it more difficult…
    Measure the resistance to ground on the coil you circled in green. What are the markings on the QFN chip circled in green?
    If there is a short on the coil, clean the solder blob on PJP8704 (effectively disconnecting the 2 traces), the measure the resistance to ground on both traces.
    OpenBoardView — https://github.com/OpenBoardView/OpenBoardView

    Comment

    • ivers
      New Member
      • Oct 2018
      • 7
      • Norway

      #3
      Originally posted by piernov
      No boardview available for this board apparently so it makes it more difficult…
      Measure the resistance to ground on the coil you circled in green. What are the markings on the QFN chip circled in green?
      If there is a short on the coil, clean the solder blob on PJP8704 (effectively disconnecting the 2 traces), the measure the resistance to ground on both traces.
      Hi, thanks for answering. ASUS has not released any schematics for this board which I know of.

      The coil has 0.9 ohm before removing the blob, and 1.4 after.

      The QFN markings are:

      1285A
      TI 638
      A2VR

      Comment

      • piernov
        Super Moderator
        • Jan 2016
        • 4435
        • France

        #4
        Re: Asus UX360 dead and soon buried?

        Schematics are never available for newer Asus laptops… Boardview can be found sometimes, but this is a very recent one so it may take a while before we can find it on the web.

        Check the resistance to ground on the other side of the blob as well, on the bottom pins of the MOSFET just to the right of the coil for example. If there is no short on this side (system side) then the short is isolated to the creation side. If that's the case, replacing the buck controller and the 2 MOSFETs should be enough to fix this issue at least.

        The QFN is a TPS51285A then. 3V/5V buck controller (with 3V/5V LDO too).
        Makes sense with the layout of the board where the controller is located between 2 coils and 2 sets of MOSFETs. Not sure which side is which, but one outputs 3.3V and the other 5V.
        OpenBoardView — https://github.com/OpenBoardView/OpenBoardView

        Comment

        • ivers
          New Member
          • Oct 2018
          • 7
          • Norway

          #5
          Re: Asus UX360 dead and soon buried?

          Ok, thanks for the help so far piernov. I'll order up some parts and test.

          Can't seem to find the mosfet, seems like its marked with

          E4 GU6
          6SOP14
          Last edited by ivers; 10-21-2018, 08:29 AM.

          Comment

          • ivers
            New Member
            • Oct 2018
            • 7
            • Norway

            #6
            Re: Asus UX360 dead and soon buried?

            Anyone able to help out what mosfet it is? Can't seem to find anything on the markings.

            Comment

            • piernov
              Super Moderator
              • Jan 2016
              • 4435
              • France

              #7
              Re: Asus UX360 dead and soon buried?

              Could you take a picture showing the markings? (if there's any logo, particular sign, or layout to at least recognize the manufacturer)
              Otherwise a 30V at least 12A N-channel MOSFET in the correct package should be suitable.
              OpenBoardView — https://github.com/OpenBoardView/OpenBoardView

              Comment

              • ivers
                New Member
                • Oct 2018
                • 7
                • Norway

                #8
                Re: Asus UX360 dead and soon buried?

                There is no markings on it, just E4 GU6 6SOP14 as I can see in the microscope..

                Comment

                • on/off
                  Badcaps Veteran
                  • Oct 2016
                  • 333
                  • Indonesia

                  #9
                  Re: Asus UX360 dead and soon buried?

                  Probably Niko Sem N-Channel PEA16BEA or PEA28BEA

                  Check this link

                  Comment

                  • ivers
                    New Member
                    • Oct 2018
                    • 7
                    • Norway

                    #10
                    Re: Asus UX360 dead and soon buried?

                    Sure looks like it. THanks on/off.

                    Comment

                    • Conste
                      Badcaps Veteran
                      • Oct 2018
                      • 235
                      • Germany

                      #11
                      Re: Asus UX360 dead and soon buried?

                      Hello,
                      Did you manage to repair the board? Guess I have the same fault...

                      Comment

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